不可能是可能的！
>但我需要从 MySQL 中途获取输出以获取请求。有人有这个食谱吗？
这是我的解决方案演示：
#!/bin/bash
################################################################################
# Bash synchronous client-server #
# or #
# Bash parallel processes with synchronized rendezvous points #
# or #
# Bash interprocess communication with named pipes #
################################################################################
#Declare your session 'globals'
args= #command line arguments are stored here
DIR= #script's current path is stored here
#Early store your bash args before you lose them
for arg in "$@"; do
args[i]=$arg
(( i+=1 ))
done
################################################################################
## Initialize constants ##
#------------------------------------------------------------------------------#
# Explain more... #
################################################################################
function init_vars() {
#absolute path of this script
DIR=$( cd "$( dirname "$0" )" && pwd )
#global MYSQL_PASS is defined in ~/.profile
#this is the file where we store MySQL root password
if [[ ! $MYSQL_PASS ]]; then
MYSQL_PASS='.mysqlpass'
fi
#do some other stuff here...
}
################################################################################
## Rotate over passed arguments ##
#------------------------------------------------------------------------------#
#Parse array 'args' based on the logic of your command line argument syntax #
#Say, '--db <database>' denotes the processing of one database, '--db all' of #
#all databases etc. #
#Linux utilities have contradicting rules for such kind of argument processing #
#(full of crap!), i.e. see tar: tar -xvf or tar --xfv or tar xvf, mysql -p #
#<pass> or mysql -p=<pass> or mysql -p'<pass>' (???) #
################################################################################
function parse_args() {
#your logic goes here
}
################################################################################
## Opens a MySQL client session ##
#------------------------------------------------------------------------------#
# For security reasons password is kept in a file given by MYSQL_PASS. #
################################################################################
function mysql_client() {
mysql --host=127.0.0.1 --port=3306 --default-character-set=utf8 -u root -p"$( cd $DIR; cat $MYSQL_PASS )"
}
################################################################################
## A job dispatcher ##
#------------------------------------------------------------------------------#
# This thread initiates the workers and also reads intermediate results from #
# the spawned jobs. We don't want to parallelize the whole part of a job but #
# rather to put some parts to run in parallel with the dispatcher and some #
# parts in a sequential order determined by what we call rendezvous points. #
# See the diagram: A, B, C, D, E and F are events or actions during the life of#
# a program. #
# #
# dispatcher #
# | start #
# A ----------------> worker #
# | | #
# B (read blocks) C #
# | signals | #
# B (unblocks)<--------------- D (write blocks) #
# | | #
# E (1st set of results) F #
# | | #
# We can only guarantee that E comes after D or, D->E in time but E->F or F->E #
# and B->C or C->B (we don't care) #
################################################################################
function dispatcher() {
#go to the directory of this script
cd $DIR
#make a temporary directory secured in 'time & space'
TMPDIR=$( mktemp -d XXXXXXXXXX )
#catch exit of this script and delete temporary folder
trap 'cd $DIR && rm -rf "$TMPDIR"' EXIT
#move into the temporary folder
cd ${TMPDIR}
#create named pipes-global to all functions of this script
TMPSQL=mysql-$RANDOM.$RANDOM.$RANDOM.$$
TMPSCRIPT=myscript-$RANDOM.$RANDOM.$RANDOM.$$
mkfifo $TMPSQL
mkfifo $TMPSCRIPT
#exec 3<> ${DIR}/${TMPDIR}/$TMPSQL || (echo 'error'; exit 1)
#exec 4<> ${DIR}/${TMPDIR}/$TMPSCRIPT || ( echo 'error'; exit 1)
echo '===1.PARENT=== Starting background jobs...'
echo 'We can guarantee the succession only of 2->3,4 and 5->6,7 but NOT 3->4 or 6->7!'
worker &
##################################
cat $TMPSQL #make a blocking read!
##################################
echo '===4.PARENT=== ...1st query has been read'
##################################
cat $TMPSQL #make a blocking read!
##################################
echo '===7.PARENT=== ...2nd query has been read'
#don't you dare to exit!
##################################
cat $TMPSQL #make a blocking read!
##################################
}
################################################################################
## A job spawned by the dispatcher ##
#------------------------------------------------------------------------------#
################################################################################
function worker() {
echo "===2.CHILD=== Executing 1st query......writing to $TMPSQL"
#the dash symbol '-' makes tabs at the beginning of line to be
#ignored inside the here-doc but improves formation!
mysql_client <<- QUERY
\! tee $TMPSQL
use test;
select * from customers;
\! echo '===3.CHILD=== End 1st query'
#####################################
#\. $TMPSCRIPT
#####################################
QUERY
echo "===5.CHILD=== Executing 2nd query......writing to $TMPSQL"
mysql_client <<- QUERY
\! tee $TMPSQL
use test;
select * from cars;
\! echo '===6.CHILD=== End 2nd query'
#####################################
#\. $TMPSCRIPT
#####################################
QUERY
echo '===8.CHILD=== End of background jobs'
echo > $TMPSQL
}
#parse command line arguments
parse_args
#initialize variables
init_vars
#call dispatcher
dispatcher
假设您有一个“测试”数据库，那么您可以看到以下输出：
===1.PARENT=== Starting background jobs...
We can guarantee the succession only of 2->3,4 and 5->6,7 but NOT 3->4 or 6->7!
===2.CHILD=== Executing 1st query......writing to mysql-30627.1495.5394.7533
===4.PARENT=== ...1st query has been read
id_customer firstname secondname
1 John Pincolo
2 Mark Denonto
3 Ann Curtis
4 Jeny Wirth
===3.CHILD=== End 1st query
===5.CHILD=== Executing 2nd query......writing to mysql-30627.1495.5394.7533
===7.PARENT=== ...2nd query has been read
id_car type plate date_rent date_returned
1 fiat BG-457 2012-07-18 00:00:00 2012-07-20 00:00:00
2 renault AS-1234 2012-07-20 00:00:00 2012-07-25 00:00:00
3 fiat JYB-2856 2012-06-23 00:00:00 2012-06-24 00:00:00
===6.CHILD=== End 2nd query
===8.CHILD=== End of background jobs
如您所见，我的第一个数据库结果集在 2 到 5 之间！
您想要查询和“主”程序之间的中间结果，并且您拥有它们！
您可能想知道：“嘿，我想获得一个数据库锁，在我的'主'程序执行其他操作时停止会话以冻结！”
嗯，也有答案。
函数 'worker' 有 2 个注释命令：
#####################################
#\. $TMPSCRIPT
#####################################
通过启用它们，您的执行会挂起！！！而已！现在，您可以在调度程序中开始做事，当您完成发送一个像这样的“回声”时：
echo > $TMPSCRIPT
通过将这行代码添加到我们的工作线程，我们将调度程序和工作线程都转换为阻塞线程：现在两者都互相监听。示意图：
dispatcher
| start
A ----------------> worker
| |
B (read blocks) C
| signals |
B (unblocks)<--------------- D (write blocks)
| |
E (1st set of results) F
| |
| G (read blocks)
| signals |
H ----------------> G (unblocks)
| (write blocks) |
如果你需要更多的刺激，发送什么
echo 'set @x=@x+1;' > $TMPSCRIPT
其中“@x”是用户定义的变量！我们这里有什么？好吧，我们只是将实时代码“注入”到我们的 sql 作业中！非常棒！！！
现在，可以获取数据库的 LOCk，进行逻辑备份，停止并继续 mysql 客户端，在数据库 LOCK 仍处于活动状态时为所欲为！
它可以更好：创建二进制备份怎么样？ （刚刚每年为您节省了 2,000-10,000 美元，请参阅：https://shop.oracle.com）
总比更好：可以锁定一堆说 10 个数据库并开始备份，第一个完成的调度程序向调度程序发送确认，调度程序在列表中添加另一个数据库，直到它变为空！
请记住，每个工人都需要两把锁来进行双向锁定。
我们甚至可以同时启动 3 个调度程序，因为它们在空间上是独一无二的，因此不可能面对它们的命名管道的冲突。
这是我的 2,000 美元建议
甜！
（百人队）